Find Mr. Freeze

Mr. Freeze is located somewhere in the sprawling metropolis of Arkham City, but locating him is made easier by the Climate Analyzer. Head north to see the temperature dip steadily, affirming you are headed in the right direction.

By the time you reach the right location, Joker is already one step ahead of you and has sent in his troops to get into the Gotham City Police Department. They'll struggle to open the shutter doors to the building, but a Remote Electrical Charge will budge it just enough for you to slide under.

Grab the broadcasting signal chip from the body by the door, decode the broadcast, and then head inside.

Five of Penguin's goons, all armed, currently occupy the GCPD. All the goons have their heart rates monitored, so Penguin -- and by extension the rest of the hit squad -- will be alerted the instant anyone is taken out of commission. If you make too much noise, Batman won't be able to withstand the sheer amount of heat these guys will shower on him.

You'll need to go about this discreetly and swiftly. There are enough high perches around for you to pick and choose your kills. After methodically overpowering the gang, the last one standing will voluntarily surrender, allowing you to interrogate him on the whereabouts of Freeze.

One cool thing to note: Activating the electromagnets around the room when a guard is in the vicinity will temporarily disarm him, allowing you to go for the swift takedown.

On this note, Penguin traps you in the GCPD, but you'll be introduced to hacking via the Cryptographic Sequencer. First, pop open the floor grates and crawl under to access the security room next to the GCPD entrance and use the Sequencer to interact with the security panel. Successfully hacking the system gets you out of here and onto the next location: the museum.